Document holders of this type which are designed for use in suspension filing systems are well known in the prior art. For example, see particularly the devices described in U.S. Pat. No. 4,056,296, U.S. patent application Ser. No. 741,237, and U.S. Pat. No. 4,171,854. These references disclose improved embodiments of a document holder comprising a body shaped like a back or spine of a book. The body is formed by two similar sections which are permanently connected together so that they can be swung toward and away from one another, at least two mounting pins which are suitable for holding and positioning sheet materials between the two sections, and spring-locking means apt to prevent rotation of the two sections and the release of the sheet materials, which are captivated through their holes on the mounting pins between the two sections of the holder. In this position, portions, which are suitably, symmetrically shaped on both sections of the holder form hooking means for mounting the holder on rails or similar supports provided in suspension filing systems.
A first drawback of the above mentioned devices results from the structure thereof. Since the holder body is made as an integral unit, mutual rotation of the two body sections is obtained by longitudinally weakening the body in its narrow central strip-shaped portion so that a hinge is formed. Although this hinge is easy to make, it obviously tends to break after repeated opening and closing operations of the document holder, thus putting the holder out of use. Furthermore, the hooking means are provided in fixed positions on the body of the holder, whereas the distance between the supports is not always the same from one suspension filing system to another.
Therefore, it is necessary to produce document holders having different lengths.
Since it is desiderable to adjust the document holders to the amount of sheet materials to be contained, it is necessary to design them with different transversal dimensions. Furthermore, the above mentioned holders are not able to hold sheet materials without holes for the mounting pins. It should also be be pointed out that it is impossible to put such holders which are designed to be placed into a suspension filing system into cabinets.